转化率是对于反应物而言,收率是对于目的产物而言,叫法有所不同,但对于同一个反应它们在数值上是相等的。
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—If there are ________ people driving, there will be ________ air pollution.—Yes, and the air will be fresher.
A. less; less
B. less; fewer
C. fewer; fewer
D. fewer; less
Of all the students he is more clever. 横线上的词正确吗?
A. 对
B. 错
She is more prettythan her sister.横线上的形容词使用正确吗?
A. 对
B. 错
物质的粒子跃迁分辐射跃迁和非辐射跃迁,简述这两种跃迁的区别。